One of the most difficult problems faced by farmers is the control of infestation insects on growing and cropping plants. Although farmers have been able to control such insects through the use of pesticides, the use of pesticides is known to be toxic to other plant and animal species, including humans. Because pesticides often seep into the ground water, they can travel from the crops and harm the entire environment surrounding the crops. Further, pesticides may not be the solution for eliminating all harmful insects. While some insects may be affected by the pesticides, others in the area may not be affected. Beneficial insects may be adversely affected. Insects may mutate and thus become resistant to the pesticides.
A good example of an insect that is not adversely affected by most pesticides is the whitefly. It is estimated that the whitefly caused over $500 million in damage to U.S. agricultural production in 1991 alone. Perring et. al., Evidence For a New Species of Whitefly: UCR Findings and Implications, California Agriculture, January-February 1993, p. 7. The whitefly harms crops by transmitting plant diseases, feeding on crops, and contaminating them with sticky sugars.
The difficulty in controlling the whitefly lies in the strength of their composition and ability to resist pesticides. First, in most cases, the whitefly's predator insects have been eliminated either by man's destruction of wetlands and streambeds that are habitats to beneficial predatory insects or by man's continual use of pesticides and herbicides. Further, the whitefly has shown the ability to produce a waxy enzyme that protects it against the penetration of conventional pesticides. Moreover, the whitefly has the ability to mutate and adjust its internal chemical balance to resist pesticides after a few generations of exposure. Lastly, the whitefly shows great strength in numbers due to their rapid reproduction rate combined with a tendency to accumulate on a host plant rather than voluntarily migrate far distances.
The whitefly does have some weaknesses that could be exploited in attempting to control their populations and eliminate them altogether from crop. For instance, whitefly are surface dwellers, i.e., they do not live below the ground. They have a very small body mass. Their main source of protection is the wax-like covering described above. They are soft-bodied and are a desirable food source for many types of predatory insects. Whiteflys tend to establish their residency, i.e., their life cycle adjusts to the life cycle of their host's ability to create food (field or tree crops). As is common to all living organisms, the whitefly's ability to live is dependent upon its ability to maintain specific body temperature, plus or minus a certain number of degrees.
S. V. Bleshinskii, et. al. of the Institute of Inorganic and Physical Chemistry, Academy of Sciences of Kirgiz SSR in the Academy of Sciences of the Kirgiz SSR, No. 2, pp. 37-39, 1983, described their discovery that, on a purely experimental basis, the temperature of water at which plants are not damaged upon contact, but insects are killed is 60-65.degree. C., for a time period of 0.2 sec. All but one of their experiments utilized the addition of chemicals to the water, namely household soap. Although Bleshinskii et. al. may have recognized that insects could be eliminated with the use of heated water, Bleshinskii et. al. did not discuss the temperatures, times, apparatus, or other parameters necessary for the economically-feasible, large scale elimination of whitefly and other insects, without causing damage to the crops.
Further, Thompson, U.S. Pat. No. 5,297,730, has used heated water to control weeds and undergrowth, as well as insects. Although Thompson recognized that heated water can be useful to eliminate insects, Thompson made this recognition in conjunction with his use of heated water to eliminate the plants as well. Thus, Thompson's method and apparatus would be of no use in eliminating insects from crops, because the crops would be destroyed along with the insects.
Accordingly, it will be appreciated from the foregoing that there is a definite need for a method and apparatus for the non-toxic control of whitefly and other small bodied infestation insects on growing and cropping plants. The method should effectively eliminate all of the insect infestation in the treated areas, without harming the growing and cropping plants. The method should avoid all uses of pesticides or other chemicals that could cause harm to the environment, including groundwater. The method should also prevent the insects from being able to avoid the effect of the treatment by mutation in the body chemistry. The method should also not adversely affect the long-term activity of pollinating or beneficial predatory insects. Further, the materials, apparatus, and energy requirements of the method should be of such a cost that the process is economically feasible. The present invention meets these needs.